Experimental Investigation of the Coupling Between Aero- and Hydrodynamical Loads On A 12 MW Semi-Submersible Floating Wind Turbine

Model tests were performed with a model of the INO WINDMOOR 12 MW floating wind turbine in the Ocean Basin at SINTEF Ocean. The tests were done at a scale of 1:40. Real-Time Hybrid Model testing was used for the modelling of the wind turbine rotor and aerodynamic loads. A subset of the results is analysed to study the influence of the wind on the platform motions, the acceleration at tower top, the loads at base of tower and the relative wave elevation. The study is based on the comparison of the quantities of interest for different tests with the same moderate sea-state but with different wind modelling: no wind, constant thrust force, turbulent wind of 11.5 m/s and turbulent wind of 25 m/s. The wind modelling has a minimal influence on the platform surge and pitch response in the wave-frequency range. On the other hand, the aerodynamic loads, including wind turbine controller dynamics and turbulent wind, has an important impact on the low-frequency surge and pitch response. The aerodynamic loads are important for the loads at tower base due to the dominance of the tower-RNA induced gravitational loads at low-frequency. Maximum relative wave elevation was found to be mainly dependent on the thrust induced mean pitch angle.